Merge pull request #6926 from Lyndon-Li/backup-pod-spread-evenly

Issue 6734: spread backup pod evenly

changelogs/unreleased/6926-Lyndon-Li

@@ -0,0 +1 @@
+Partially fix #6734, guide Kubernetes' scheduler to spread backup pods evenly across nodes as much as possible, so that data mover backup could achieve better parallelism

pkg/exposer/csi_snapshot.go

@@ -361,6 +361,12 @@ func (e *csiSnapshotExposer) createBackupPod(ctx context.Context, ownerObject co
 	var gracePeriod int64 = 0
 	volumeMounts, volumeDevices := kube.MakePodPVCAttachment(volumeName, backupPVC.Spec.VolumeMode)
 
+	if label == nil {
+		label = make(map[string]string)
+	}
+
+	label[podGroupLabel] = podGroupSnapshot
+
 	pod := &corev1.Pod{
 		ObjectMeta: metav1.ObjectMeta{
 			Name:      podName,
@@ -377,6 +383,18 @@ func (e *csiSnapshotExposer) createBackupPod(ctx context.Context, ownerObject co
 			Labels: label,
 		},
 		Spec: corev1.PodSpec{
+			TopologySpreadConstraints: []corev1.TopologySpreadConstraint{
+				{
+					MaxSkew:           1,
+					TopologyKey:       "kubernetes.io/hostname",
+					WhenUnsatisfiable: corev1.ScheduleAnyway,
+					LabelSelector: &metav1.LabelSelector{
+						MatchLabels: map[string]string{
+							podGroupLabel: podGroupSnapshot,
+						},
+					},
+				},
+			},
 			Containers: []corev1.Container{
 				{
 					Name:            containerName,

pkg/exposer/types.go

@@ -23,6 +23,8 @@ import (
 const (
 	AccessModeFileSystem = "by-file-system"
 	AccessModeBlock      = "by-block-device"
+	podGroupLabel        = "velero.io/exposer-pod-group"
+	podGroupSnapshot     = "snapshot-exposer"
 )
 
 // ExposeResult defines the result of expose.